2.24.0 is still covered by the old policy

“Prior to Mbed TLS 2.24” suggests that 2.24 itself didn't use the old
policy anymore, but it did. Change to “Until”, and also give the exact
version number “2.24.0”.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/ChangeLog.d/00README.md b/ChangeLog.d/00README.md
index ec61c52..d2ea73d 100644
--- a/ChangeLog.d/00README.md
+++ b/ChangeLog.d/00README.md
@@ -22,7 +22,7 @@
 * Changes to parts of the code base that users don't interact with directly,
   such as test code and test data.
 
-Prior to Mbed TLS 2.24, we required changelog entries in more cases.
+Until Mbed TLS 2.24.0, we required changelog entries in more cases.
 Looking at older changelog entries is good practice for how to write a
 changelog entry, but not for deciding whether to write one.